Cinematorgraphy



D. F. oMsTocK CINEMATOGRAPHY Filed Jan. 8, 192.3

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Patented Sept. 6, 1927.

UN'IT'ED. 'STATES PATENT OFFICE.

DANIEL F. COMSTOCK, OF-BOSTON, MASSACHUSETTS, ASSIGNOR T0 TECHNICOLOR i MOTION PICTURE or MAINE..

Application filed January 8, 1923. Serial No. 611,257.

An inherent fault of cinematographic films is their tendency to shrink and expand under varying conditions of moisture. For example, an ordinary cinematographic film shrinks from one-tentli to one-fourth'per cent in the wetting and drying processes incdent to the developing process, this shrinkage varyingapproximately ten per cent of itself for similar pieces of film treated in the same general way; fresh film shrinks about one-twentieth per cent per day for many days if unsealed; aiidfilm expands approxi-mately One-hundredth per cent `for .each added 'degree of humidity in the surrounding atmosphere.

.While this shrinkage and expansion is more or less troublesome in the black-andwliite branch of the art, it involves difficulties of the firsty order in the color branch .of the art Where the complemental pictures representing the different color aspects niust be registered With a high degree of' accuracy, the registration being effected in the projection stage .of certain processes, such as most additive processes, and in the exposing or printing stage'in other processes, suchas most subtractive processes.

For example in producing color cinematographic films by imbibition of dye between the printed film and one or more matrix films, Where a plurality of series of images (e. g. one series representing t-he red aspect and another series representing the green aspect of the scene) are printedin superposition Ona single film, either on the same side or on Opposite sides of the film, the complemental images must be registered With re,

speet to each other with extreme accuracy, viz., Within approximately onesthousandth of an inch of exact registry; an`d operating against this accurate registration are many troublesome factors chief of which is the tendencyof the matrix films to shrink in the interim between the format-ion of the images thereon and the reproduction of 'the images on the printed film, this shrinkage notv only changing the size of the images but also al- ,tering the relationship between the images andr theircorresponding sprocket holes or other registering openings. Moreover, since imbibition processes ordinarily require relatively long lengths Of film to be simultanecult-y is rendered still more complex by un-r equal shrinkage of the respective matrices.l

Vliile air shrinkage is considerable the aforesaid shrinkage is caused principally by the wet process through which the films pass in the production of the images thereon. For example, iii preparing imbibition matrices by a photographic process the images are first printed on the film and subsequently developed and otherwise subjected to liquid treatment which gives rise to the shrinkage.

The objects of 'the present invention are to overcome the shrinkageldifficulties in cinematograpliic films and to make it possible to reproduce the images with accuracy and uniformity; and more particularly to provide a vmaster or matrix film Whose dimensions are substantially unaffected by moisture, which is less subject to tearing or other mechanical injury than the ordinary film,

and which is much more'durable in use.

In one aspect the invention comprises a .eineniatographic strip or film .having cenientcd or otherwise attached thereto a backing, sucli as a. steel or other metallic ribbon, Whose dimensions are substantially unaffect- 'ed by moisture and Which has sufficient' strength to prevent substantial shrinkage or expansion of' the film. The aforesaid backing is provided With a series of openings for positioning succeeding sections of the film (they film also having corresponding Openings if the film extends the full Width of the backing)A and the images or pictures .on the film bearuniform relation to the openings by which they are positioned respectively. A backing in the form of a thin steel ribbon offers satisfactory strength and flexibility; and a copper surface (either a copper alloy or relativelv pure copper) adheres especially well to the film. Consequently, the backing is preferably in 'the form of a thin steel ribbon copper plated. The backing is also preferably lacquered and dried before the vfilm is cemented thereto as will appear hereinafter.

In another aspect the invention consists 1n ii the methodI of producing einematographi'c'A films which comprises mounting alight-sensitive strip on a band or backing such -as above referred to, forming a series of p10- tures on the strip by a process involving a wet treatment, as by exposure and development, the latter being effected while the film is mounted on the band or backing so that` exposedportions maybe etched ofi without" detaching the exposed portions from the sup ort. Consequently, when the aforesaid bac ing is opaque, as in the case of,a steel ribbon, the photographic strip is exposed through the back before being cemented or4 otherwise mounted on the backing andv is then mounted on the backing before being developed or otherwise subjected to conditions which would alter its dimensions. With the strip thus supported and held against shrinkage or expansion the images or pic-` tures formed thereonl are held in uniform and fixed position relatively to each other and to the sprocket holes or other positoning openings by whichthey are respectively registered, whereby theymay be reproduced in accurate registry by m'eans of the sprocket holes or otheropenings notwithstanding the inherent-tendency of the photographic layer of the film or band to expand and shrink as a result of wetting and drying or changes in the conditions of moisture to which it is subjected.

In a more specific aspect the invention consists in reproducing cinematographic films by forming an lmbibition matrix on a flexible band such as above referred to, andforming pictures on another film by transfer of dye between the matrix and the other film, the band serving to prevent substantial shrinkageor expansion of the matrix as a result of wetting the matrix with the dye, which wetting is repeated for each film printed from the matrix.

As an illustration one embodiment of the invention is shown in the accompanying drawing, in which,'

FgQl is a face view of the cinematographic film;

Fig. 2 is an edge view of the. film and a backing before being attached together;

Fig. y3 is a similar view of the parts after being joined Fig. 4 is a section and f 'Fig. 5 is a section similar to Fig. 4 'showing one method of printing.

on line 4 4 of Fig. 3;

. In the vdrawings indicates a photo? graphic strip comprising a light-sensitive or image layer I and a supporting layer C which may be Celluloid, and B indicates a backing such'as above'refeire'd to.

A backing of brass can be readily ccmented to a Celluloid film but such a backing is easily dented. A backing of steel ribbon has lthe necessary strength and flexibility and is not'easily dented. About four-thousandths of an inch is a satisfactory thickness for the backing. With certain cements, such as the cement hereinafter described, the adhesion between the film anda steel backing is improved by copper plating the backing, either with copper or an alloy 'of copper. The plating may be carried on continuously as, for example, by continuously;` feedingv the steel ribbon through tl'iefollowing stages in succession; acid bath Water bath, caustic scrubber, water bat electrol icA bath, washer, acid bath, washer and rier.` The adhesion is alsoI improvedbycating the backing with a lacquer, such as Duponts pyralin lacquer, `thel lacquer being dried prefeiably at a temperature of about 120o to 125 A suitable cement vfor use with a film whose base is celluloid comprises amyl acetate with an admixture-of a small amount of camphor, theacetate serving as a Celluloid solvent to soften the surface of the Celluloid and render it adhesive. When the film and backing are brought together in the cementing process they are preferably pressed togetlier as by feeding them between pressure rollers.

been cemented together the resulting product 'is preferably subjected to a temperature of utes. For some urposes the lacquering and .cementing may e effected in a single stage by mixing the lacquer and cement (e. g. l pyralin lacquer and amyl acetate), using the mixture as a cement between the film and an unlacquered backing, and subsequently drying the combinedfilm and backing atapy.proximately 125o F.

For certain uses, for example where the film'need'not be exposed until after it has been joined to the backing, the combined film and backing may be perforated as a unit; in this case the photographic film may if desired be confined to the space between the vperforations in the backing. I

When the film and lbacking are joined after being perforated the joinder may be effected by ap aratus such as disclosed in the application o Troland and Ball, `Serial N o. 500,842, filedSeptenber l5, 1921.

In makihg matrices of the relief type, the film is preferably printed through the back with the images .in' uniform relation to the perforations by. which they the' order of 125o F. for about thirty min- After the film and backing have 'i another matrix the green aspect.

- successively printed by imbibition on the same blank film, the complemental images being printed in accurate registration by virtue of the backings holding the matrix images in the same relationship to the perforations by which they are registered with l corresponding perforations in the blank film.

Instead of using the films on the backings asmaster or' matrix films they may be suitably colored (e. g. red and green, re-. spectively) and then cemented together face to face, after Which the backingsmay be stripped off leavinga substractive'tWo-color film both of Whose outer faces are Celluloid. The coloring dyes may be restrained from migrating from one film to the other by 'mordantingl `Where the backings are to be stripped oftI .a less tenacious cement should be used, for example shellac. l

The film to be printed may likewise be mounted on a metallic ribbon or other flexible band Whose dimensions are substantially unaffected by `moisture and which has sufficient vstrength to prevent suibstantial shrinkage or expansion of the film. This is particularly advantageous in producing a color film Where-aplurality of series of images representing different color aspects of the scene are successively printed from different films since the metallic backing holds the film against shrinkage or expansion in the interim between successive printings and istering pins.

also affords more accurate registration by virtue of its rigid engagement With the reg- This method of printing is illustrated in Fig. 5 where I, C B represent the image-layer, celluloideJ and backing, respectively, of the printing film and I. C and B respectively represent the image-layer, Celluloid and backing of the film to be printed. After the latter film has been completely printed it may vbe stripped off the backing B for projection. To facilitate stripping the aforesaid copper plating may be omitted and a less tenacious cement, such as a cement which does not soften the celluloid, may be used.

I claim:

l. An article of the character described comprising a cinematographic film and a `2. An article of the character described-1 comprising a cinematographic film and a' thin steel ribbon having a copper plated surface adhering to one side of said film.

3. The method of producing cinemato graphic films which comprises forming latent images ou a photographie strip by exposurevthrough the back, mounting the strip on a flexible backing Whose dimensions are substantially unaffected byl moisture and.

Which has sufficient strength to counteract shrinkage or expansion' tendencies of the strip, and subsequently developing the latent images. U 4. The method of producing cineinatographic films which comprises forming las tent images on a photographic strip by eX- posure through the back, cementing they strip to a flexible metallic backing, and subscquently developing the latent images.

5,'The method of producing c'inemato- I graphic films'wliich comprises forming 4registering openings in a photographic strip at recurrent vintervals, forming latent images von said strip in uniform .relationship to said openings, mounting the strip on a flexible backing whose dimensions are substantially unaffected by moisture and which has suffi.- cient strength to counteract shrinkage or eX- paiision tendencies of the strip7 'with said openings in uniform vpositional relation to corresponding openingsv in the backing, and

subsequently developing the latent images. G. The method which comprises forming on a cineinatographic film a series of images representing successive time phases of an 'object-field, andy with the images accurately in standard spated relationship mounting ythe film on a flexible band whose dimensions are substantially unaffected by moisture and Which has sufficient strength to counteract film.

comprising a'celluloid strip having thereon a series of images representing successive time phases of an object-field, and fast to one side of said strip throughout the imago regions a flexible band of material Whose dimensions are suiistautiallyunaffected by moisture and which has sufficient strength to prevent substantial shrinkage or expansion of said strip.

8. An article of the character described comprising a Celluloid strip having thereon a series of images representing successive time phasesV of an object-field, and a thin metallic ribbon continuously fastened to one side of said sti-ip. .Y

9'. An article of the character described comprising a celluloid strip having thereon va series of images representing successive 7; An 'article of the character described;

a series of images representing successive time phases of an object-field, and a thin metallic ribbon having a copper Surface adhering to one side of said strip.

1l. An article ofthe character described comprising a Celluloid matrix having there.

on a series of relief images representing successive -time phases of' an object-field, and fast to one side of said matrix throughout the image regions a flexible band of material Whose dimensions are substantially unaffected by moisture and which has sufficient p strength to prevent substantial shrinkage or I3. The art of cinematography which comprises forming a cinematographic film of flexible material Whose dimensions are substantially unaffected by moisture. and which has sufficient strength to counteract shrinkage or expansion tendencies of photographic film, coating said flexible material with binding material, and sticking to said coating a photographic film.

A 14. The method of producing cinemato graphic film which comprises forming latent images on a photographic strip and subsequently inounting'the strip on a flexible backing whose dimensions are substantially un.r

affected by moisture and which has-suflicient strength to counteract yshrinkage or expansion tendencies of the strip.

Y 'Signed by me at Boston, Massachusetts, this 28th day of December, 1922.

DANIEL F. ooMsTooic 

